Cardiovascular comorbidities, inflammation, and cerebral small vessel disease.

Cerebral small vessel disease (cSVD) is the most common cause of vascular cognitive impairment and affects all levels of the brain's vasculature. Features include diverse structural and functional changes affecting small arteries and capillaries that lead to a decline in cerebral perfusion. Due to an ageing population, incidence of cSVD is continually rising. Despite its prevalence and its ability to cause multiple debilitating illnesses, such as stroke and dementia, there are currently no therapeutic strategies for the treatment of cSVD. In the healthy brain, interactions between neuronal, vascular, and inflammatory cells are required for normal functioning. When these interactions are disturbed, chronic pathological inflammation can ensue. The interplay between cSVD and inflammation has attracted much recent interest, and this review discusses chronic cardiovascular diseases, particularly hypertension, and explores how the associated inflammation may impact on the structure and function of the small arteries of the brain in cSVD. Molecular approaches in animal studies are linked to clinical outcomes in patients, and novel hypotheses regarding inflammation and cSVD are proposed that will hopefully stimulate further discussion and study in this important area.

Update of Immunosenescence in Cerebral Small Vessel Disease.

Aging of the central nervous system (CNS) is closely associated with chronic sterile low-grade inflammation in older organisms and related immune response. As an amplifier for neuro-inflammaging, immunosenescence remodels and deteriorates immune systems gradually with the passage of time, and finally contributes to severe outcomes like stroke, dementia and neurodegeneration in elderly adults. Cerebral small vessel disease (CSVD), one of the major causes of vascular dementia, has an intensive connection with the inflammatory response and immunosenescence plays a crucial role in the pathology of this disorder. In this review, we discuss the impact of immunosenescence on the development of CSVD and its underlying mechanism. Furthermore, the clinical practice significance of immunosenescence management and the diagnosis and treatment of CSVD will be also discussed.

An IL-18-centered inflammatory network as a biomarker for cerebral white matter injury.

Chronic systemic sterile inflammation is implicated in the pathogenesis of cerebrovascular disease and white matter injury. Non-invasive blood markers for risk stratification and dissection of inflammatory molecular substrates in vivo are lacking. We sought to identify whether an interconnected network of inflammatory biomarkers centered on IL-18 and all previously associated with white matter lesions could detect overt and antecedent white matter changes in two populations at risk for cerebral small vessel disease. In a cohort of 167 older adults (mean age: 76, SD 7.1, 83 females) that completed a cognitive battery, physical examination, and blood draw in parallel with MR imaging including DTI, we measured cerebral white matter hyperintensities (WMH) and free water (FW). Concurrently, serum levels of a biologic network of inflammation molecules including MPO, GDF-15, RAGE, ST2, IL-18, and MCP-1 were measured. The ability of a log-transformed population mean-adjusted inflammatory composite score (ICS) to associate with MR variables was demonstrated in an age and total intracranial volume adjusted model. In this cohort, ICS was significantly associated with WMH (ß = 0.222, p = 0.013), FW (ß = 0.3, p = 0.01), and with the number of vascular risk factor diagnoses (r = 0.36, p<0.001). In a second cohort of 131 subjects presenting for the evaluation of acute neurologic deficits concerning for stroke, we used serum levels of 11 inflammatory biomarkers in an unbiased principal component analysis which identified a single factor significantly associated with WMH. This single factor was strongly correlated with the six component ICS identified in the first cohort and was associated with WMH in a generalized linear regression model adjusted for age and gender (p = 0.027) but not acute stroke. A network of inflammatory molecules driven by IL-18 is associated with overt and antecedent white matter injury resulting from cerebrovascular disease and may be a promising peripheral biomarker for vascular white matter injury.

Influences of the TLR4/NF-κB pathway on memory function and inflammatory factors in rats with cerebral small vessel disease.

OBJECTIVE: To explore the influences of toll-like receptor 4/nuclear factor-κB (TLR4/NF-κB) pathway on the memory function and inflammatory factors in rats with cerebral small vessel disease (CSVD). MATERIALS AND METHODS: CSVD model in rats was established. Expressions of TLR4/NF-κB-related proteins and inflammatory factors were detected. CSVD rats were treated with the TLR4/NF-κB pathway agonist and inhibitor to evaluate the regulatory effect of TLR4/NF-κB pathway on the expressions of TLR4, NF-κB p50 and NF-κB p65. Moreover, their influences on the cerebral edema, memory function and expressions of inflammatory factors [interleukin-1ß (IL-1ß) and tumor necrosis factor-α (TNF-α)] in CSVD rats were also analyzed. RESULTS: In model group, the mRNA and protein expressions of TLR4 and NF-κB-related proteins in rat hippocampus were significantly higher than those in sham group (p<0.01), and the expressions of IL-1ß and TNF-αsignificantly increased (p<0.05). The agonist lipopolysaccharide (LPS) significantly increased the proportion of TLR4-positive cells (p<0.01) and protein expression of TLR4 (p<0.01). The inhibitor CLI-095 obviously reduced the proportion of TLR4-positive cells and TLR4 expression (p<0.05). Pyrrolidine dithiocarbamate (PDTC) remarkably reduced the expressions of NF-κB p50 and NF-κB p65 in model group (p<0.05). LPS promoted cerebral edema, leading to memory dysfunction and enhanced inflammatory response in rats of model group. The inhibitor CLI-095+PDTC significantly reduced cerebral edema, lowered memory impairment and relieved inflammatory response in CSVD rats (p<0.05). CONCLUSIONS: The inhibitor of the TLR4/NF-κB signaling pathway can restore memory function and reduce inflammatory response in CSVD rats.

Trained Immunity Characteristics Are Associated With Progressive Cerebral Small Vessel Disease.

Background and Purpose- Cerebral small vessel disease (cSVD) is the major vascular cause of cognitive decline and dementia. The pathogenesis of cSVD remains largely unknown, although several studies suggest a role for systemic inflammation. In certain pathophysiological situations, monocytes can reprogram toward a long-term proinflammatory phenotype, which has been termed trained immunity. We hypothesize that trained immunity contributes to the progression of cSVD. Methods- Individuals with mild-to-severe cSVD participated in the study. Severity of cSVD was determined by the white matter hyperintensities (WMH) volume (mL) on magnetic resonance imaging in 2006, 2015, and the progression between 2006 and 2015 (ΔWMH). Cytokine production was assessed after ex vivo stimulation of peripheral blood mononuclear cells and monocytes. Additionally, monocyte subsets were identified by flow cytometry. Results- Fifty-one subjects (70±6 years, 60% men, 5.1±6.4 mL ΔWMH) were included. Circulating hsIL (high-sensitivity interleukin)-6 correlated with cSVD ( P=0.005, rs=0.40). Cytokine production capacity by monocytes was associated with cSVD progression. Basal IL-8 and IL-17 production ( P=0.08, rs=0.25; P=0.03, rs=0.30) and IL-6 production after Pam3Cys stimulation in monocytes was associated with cSVD (n=35: P=0.008, rs=0.44). Conversely, interferon (IFN)-γ production in Candida albicans stimulated peripheral blood mononuclear cells was negatively correlated with cSVD ( P=0.009, rs=-0.36). Flow cytometry revealed a correlation of the intermediate monocyte subset with cSVD ( P=0.01, rs=0.36). Conclusions- Severity and progression of cSVD are not only correlated with systemic inflammation (hsIL-6) but also with trained immunity characteristics of circulating monocytes, in terms of an altered cytokine production capacity and a shift toward the proinflammatory intermediate monocyte subset.

Could Better Phenotyping Small Vessel Disease Provide New Insights into Alzheimer Disease and Improve Clinical Trial Outcomes?

Alzheimer Disease (AD) is the most common primary cause of dementia with a burgeoning epidemic as life expectancy and general medical care improve worldwide. Recent data from pathologic studies has shown that the cooccurrence of other neurodegenerative and vascular pathologies is in fact the rule rather than the exception. In late onset AD, cerebral small vessel disease (SVD) is almost invariably co-existent to a greater or lesser extent and is known to promote cognitive deterioration. Previous observational studies and clinical trials have largely sought to divide dementia based on predominant neurodegenerative or vascular mechanisms. Given the high degree of overlap, findings from such studies may be difficult to interpret and apply to population cohorts. Additionally opportunities may be lost for uncovering novel interventions that target interactions between co-existent vascular and neurodegenerative pathologies. In the current review, we consider potential pathophysiologic mechanisms through which SVD may be associated with and promote AD pathology. In particular we explore shared environmental and genetic associations and how these may converge via neuroinflammatory pathways potentially providing novel therapeutic targets. SVD has heterogenous manifestations on cerebral imaging and at pathology. We discuss how studying SVD topography may enable us to better identify those at risk for more rapid cognitive decline and improve future clinical trial design.

Anti-endothelial cell antibodies in patients with cerebral small vessel disease.

The pathogenesis of cerebral small vessel disease (CSVD) in the elderly is poorly understood. Endothelial cell activation and dysfunction may play a causal role in the pathogenesis of CSVD. It was reported that anti-endothelial cell antibodies (AECAs) are associated with endothelial cell dysfunction and inflammation. We hypothesized that AECAs may be associated with the pathogenesis of CSVD. We examined AECAs in sera from 12 elderly subjects with CSVD, 12 elderly subjects without CSVD, and 18 healthy volunteers by 2-dimensional immunoblotting using primary cultured human brain microvascular endothelial cells as the antigen source. We identified 4 AECAs that were detected in sera from more than one-half of the elderly subjects with CSVD. Subsequently, we analyzed the target antigens of these 4 antibodies by liquid chromatography-tandem mass spectrometry. The target antigens of these 4 antibodies were tropomyosin alpha-4 chain (TPM4), vimentin, alpha-enolase, and annexin A2. Among these 4 antibodies, the anti-TPM4 antibody was significantly more frequently detected in sera from the elderly subjects with CSVD than the other subjects. We determined the anti-TPM4 antibody level in sera from 21 elderly subjects with CSVD and 25 subjects without CSVD by enzyme-linked immunosorbent assay. The anti-TPM4 antibody level was significantly higher in the subjects with than without CSVD. Therefore, an autoimmune, inflammatory process with high levels of anti-TPM4 antibody may contribute to the development of CSVD in the elderly.

Angiogenic T-cells and putative endothelial progenitor cells in hypertension-related cerebral small vessel disease.

BACKGROUND AND PURPOSE: Cerebral small vessel disease (CSVD) may be caused by endothelial dysfunction, whereas endothelial progenitor cells (EPC) may attenuate endothelial dysfunction. Their vitality is lower in CSVD. A subset of lymphocytes, angiogenic T-cells, is capable to stimulate EPC function. The purpose of our study was to explore the relation between CSVD manifestations, angiogenic T-cells, and EPC in hypertensive patients with CSVD. METHODS: We compared 32 essential hypertensive patients with CSVD (white matter lesions, asymptomatic lacunar infarcts, or microbleeds on 1.5-Tesla MRI) to 29 age-matched and sex-matched hypertensive controls. We counted angiogenic T-cells (CD3(+)/CD31(+)/CD184(+)) and putative EPC (CD31(+)/CD34(+)/CD45(-)/KDR(+)) by flow cytometry and determined EPC vitality by in vitro cluster formation. RESULTS: Putative EPC numbers were lower in hypertensive individuals with CSVD than in those without (10±7(.)10(3)/mL versus 13±6(.)10(3)/mL [median±interquartile range]; P=0.011). Angiogenic T-cell numbers were also lower in hypertensive individuals with CSVD than in those without (0.56±0.25(.)10(9)/mL versus 0.78±0.50(.)10(9)/mL; P=0.008). Higher angiogenic T-cell numbers independently related to absence of CSVD (odds ratio, 0.088; 95% confidence interval, 0.012-0.627). CONCLUSIONS: Our data suggest that angiogenic T-cells and putative EPC independently relate to radiological CSVD manifestations in hypertensive patients.